Gasket welding apparatus and method

Abstract

Bevelled end edges (37, 38) of gasket lengths (21, 36) are fused into miter joints (39) at corners (18) by welding apparatus having jig and clamp sets (64) on plates (49, 50) that are mounted on rails (59, 60) and separated by cam followers (81, 82) which interact against the bias of a spring (87) with a cam (88) which is rotated by a handler (93) on a shaft (73) to set the spacing of the sets (64). End edges (37, 38) are aligned int he spacing gap (54) against surfaces (185, 186) of a sissy bar (180) which is lifted up when the cam (88) is turned to its position of longest spacing. The bar (180) is then lowered and a heater block (29) is moved and locked into an advanced position within the gap (54) pulling a handle (115) of a rod (116), by spring finger (122) which shifts onto a lockwheel (125). The cam (88) is turned to an intermediate spacing position to melt the edges (37, 38) against the block (79), and then moved to a shortest spacing position to fuse the melted edges together. In moving from the intermediate to the shortest spacing position, the cam passes through the longest spacing position again, momentarily separating the edges (37, 38) from the block (79) and aligning the finger (122) with a lockwheel cutout (127), to return the block (79) to its retracted position under the bias of a spring (118).

What is claimed is: 
     
       1. A method for heat welding end edges of heat fusible gasket material together to form a joint, said method comprising: mounting left and right plates on a housing for relative movement with respect to one another across a gap;   supporting left and right lengths of said gasket material in channels of corresponding left and right members mounted on said housing for travel with said plates, with said end edges disposed in spaced, facing positions within said gap;   providing a heater element movably mounted on said housing, said heater element having heating surfaces;   biasing said heater element into an out-of-the-way retracted position out of said gap;   using a cam, moving said plates to set said gap to a longest spacing position;   with said gap set to said longest spacing position, moving said heater element from said out-of-the-way retracted position to an advanced position with said heating surfaces within said gap facing said end edges;   locking said heater element in said advanced position;   using said cam, moving said plates to set said gap to an intermediate position wherein said end edges are in contact with said heating surfaces;   using said cam, moving said plates to set said gap to a longest spacing position;   using said cam, moving said plates to set said gap to a shortest position wherein said end edges are in contact with each other; and   releasing said heater element to move it from said advanced position to said retracted position under action of said biasing means, automatically in response to moving said plates from said intermediate gap space setting position, through said longest gap space setting position, to said shortest gap space setting position.   
     
     
       2. A method as in claim 1, further comprising the step of cutting said end edges at opposite 45° angles to provide bevelled ends; and wherein said supporting step supports said lengths at right angles to each other. 
     
     
       3. A method as in claim 2, for heat welding end edges of gasket material having a gasket profile, and wherein said supporting step comprises supporting said lengths in left and right complementary jig and clamp sets within channels defined by gasket profile matching cavities. 
     
     
       4. A method as in claim 3, wherein said supporting step further comprises separating each clamp from its associated jig, inserting said respective length within said channel with said clamp separated, and bringing said clamp back together with said jig. 
     
     
       5. A method as in claim 1, further comprising biasing said plates together against said cam; and wherein in said cam using steps said cam is supported on a shaft, and said gap settings are made by rotating said shaft to rotate said cam. 
     
     
       6. A method as in claim 5, wherein said heater element is mounted on a carriage; and said heater element moving step comprises moving said carriage axially along said shaft. 
     
     
       7. A method as in claim 6, wherein said heater element comprises a spring finger having an end fixed to said carriage and another hook shaped free end that has a rounded leading edge; and said locking step comprises passing said free end over a lockwheel when said carriage is moved to bring said heater element into said advanced position. 
     
     
       8. A method as in claim 7, wherein said automatic releasing step comprises providing a cutout in said lockwheel, mounting said lockwheel on said shaft, and aligning said free end of said spring finger with said cutout as said cam moves through said longest gap space setting position, in travel from its intermediate to its shortest gap space setting position. 
     
     
       9. A method as in claim 1, further comprising the step of mounting a sissy bar having oppositely facing gasket gap space setting position. 
     
     
       10. A method as in claim 1, further comprising the step of mounting a sissy bar having oppositely facing gasket alignment surfaces for pivotal movement on said housing; and said supporting step further comprises pivoting said sissy bar to an "up" position; moving said gasket end edges into respective contact with said sissy bar alignment surfaces; and pivoting said sissy bar out of said gap into an out-of-the-way "down" position.